The present invention relates to an automatic sheet feeder mainly used for feeding an original sheet to a contact glass plate of an image reading machine (such as a copying machine).
When a stack of original sheets is placed on an initial tray of an automatic sheet feeder and a copying operation starts, an original sheet is taken out from the stack and the sheet is brought into a preset position on the contact glass plate of the copying machine on which the automatic sheet feeder is equipped.
The inside mechanism of the automatic sheet feeder is as follows. The uppermost (or sometimes the lowermost) sheet of the stacked original sheets is taken into the housing of the automatic sheet feeder by a taking-in roller (or rollers) and first placed at a preset adjusting site provided inside the automatic sheet feeder in order to determine the position of the original sheet (first feeding). Then the position-determined original sheet is transferred to the preset copying position of the contact glass plate by resist rollers (second feeding). Here, at the same time, the next original sheet undergoes the first feeding and is placed at the adjusting site.
After the image reading (copying operation) of the original sheet is finished, the original sheet is taken out from the contact glass plate and ejected onto a finished tray of the automatic sheet feeder by an ejecting mechanism. At the same time, the second original sheet is next fed to the preset copying position. Thus a continuous copying of a plurality of original sheets is automatically performed.
The automatic sheet feeder attached on the copying machine is electrically connected to the copying machine, and the timing of the above sheet feeding operations is controlled by command signals from the copying machine and the power is also given from the copying machine.
When the operator opens a cover of the housing of the copying machine in order to, for example, eliminate a jammed sheet, the power to the main parts of the copying machine is automatically cut for safety. In this case also the power to the automatic sheet feeder is cut. The problem is that the data in the volatile memory of the control system of the automatic sheet feeder is lost when the power to the automatic sheet feeder is cut. Among the data lost are data about the condition of the automatic sheet feeder and the position of the original sheet taken inside of the automatic sheet feeder. Therefore, when a continuous copying operation is interrupted by an opening of the cover (by a jamming trouble, for example), the automatic sheet feeder cannot resume the continuous copying operation correctly after the cover is closed again. In concrete, the trouble is that the original sheet on the contact glass plate at the time of jamming trouble during a continuous copying operation can never be copied: when the jammed paper is eliminated and the copying operation is restarted, the original sheet (which has not been copied) is ejected from the contact glass plate because the automatic sheet feeder executes a preset initializing routine. Thus the original sheet must be reset on the initial tray to correctly resume the continuous copying operation.